U.S. Pat. No. 4,757,354 issued Jul. 12, 1988 to Sato et al. for Projection Optical System discloses a projection optical system including refraction sub-system and a cata-dioptric subsystem optically connected to each other and is used for photolithography used in producing integrated circuits, large-scale circuits, or the like.
U.S. Pat. No. 4,937,424 issued Jun. 26, 1990 to Yasui et al. for Laser Machining Apparatus discloses a laser machining apparatus including a laser resonator capable of producing a laser beam having a filled-in intensity distribution pattern and a condensing device for converting the beam into a suitable beam to perform an intended machining.